Wireless sensor networks are often used for event detection applications, which require a certain level of reliability and timeliness while minimizing energy consumption. Existing work considers reliability, timeliness and energy consumption largely in isolation. This paper proposes a solution to satisfy these conflicting requirements by using biologically-inspired mobile agents. The problem is formulated into an NP-hard problem, the Vehicle Routing Problem, and decentralized and centralized heuristics are developed to govern agent behaviors. Simulation results show that proposed solution allows agents (i.e., sensor applications) to effectively balance the tradeoffs among reliability, timeliness and energy efficiency and outperform an existing similar mechanism.